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Posted: 10/16/2015 7:48:43 PM EDT
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I have this new upper in 300AAC. Was having tons of problems with it failing to fire and failing to extract. I picked up some PTG Go No-Go gauges from Midway to check the chamber. The bolt closes on both gauges.
Is this a problem? if so, does that mean it is a bad barrel or is this something I can fix? Any assistance would be greatly appreciated, Thanks. |
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If the bolt closes on the NO GO gauge, that means that the chamber is "longer" than is should be. It's not necessarily dangerous, but "just closing" on a NO GO gauge is equivalent to saying your chamber is shot out. You could try the gauges with a different bolt - if the NO GO gauge is just barely allowing the bolt to close, a different bolt might be all you need. Otherwise, yes, it's a barrel issue.
As for failures to fire or failures to extract, those could both be due to a bolt problem. Or it could be something else, especially the failures to fire. For clarity, how are the extractions failing? Is the case coming out of the chamber and maybe staying in the upper? |
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GH is dead on.....depends on how deep the chamber is......if it is too deep....the extractor can push the round in deep enough where the firing pin can't hit it........if this happens I'm guessing extraction of an unfired round is brutal.....look on the extractor...if the finish is worn on either side of the false lug it is a sign that the extractor isn't clipping over the case rim and dragging on the barrel extension when extracting the round.
If you can pull the barrel and measure form the base of the go gauge to the rim of the barrel extension it'll tell us a LOT. |
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I am using a brand new seekins precision upper. With their bolt in, I tested several rounds with a high fail rate of rounds not firing and/or not extracting. The rounds all had some sign of dimpling from the firing pin strike (mostly looked like light primer strikes). IF the round did not fire, it did not extract under most conditions. Some cases the round fired and still did not extract. Every case that did not extract, I had to pop it out with a cleaning rod. They were not tight, just a little tap and it popped right out.
In working with seekins, they are sending me a new BCG since the bolt on this one had some odd coloring and corrosion going on. I have a backup BCG that is brand new, never used, I recently pick up from primary arms. This is what I am testing the gauges on, a brand new BCG. Closing the BCG on both gauges feels similar. Doesn't take a lot of pressure to close the bolt all the way. I did remove the extractor to make this a bit easier. I should mention some of the cases that did fire on the original BCG, I noticed the primers were slightly popping out of their pocket. Also, 2 rounds would not chamber at all. I could be dealing with ammo problems and will try to eliminate that with another brand of ammo. I think my main concern is that the bolt does close on the No Go gauge. Not sure if I should try to shoot it again with this other BCG to see if the problem still exists? |
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A person would generally follow up a failed No-go gage test with a Field gage test.
A new barrel should not fail a No-go gage. Also failing a Field gage would mean it was not safe to fire. The tolerance range on a bolt is .003” so it is certainly possible a different bolt will solve the headspace issue. Given the primer condition you are seeing I would not fire that weapon until it was checked with a Field gage. |
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They are correct in saying a No Go Gauge is exactly what it says. It means it should not go into battery. If it does and as you say the primers are backing out I would not fire the weapon but contact the people that you purchased the barrel from and ask them what you need to do in order to have the barrel you purchased from them either fixed and or replaced after you make certain it is not a bad bolt.
There are ways around this if you just really wish to put the work in. But it is not something I would do in an AR. And that would be to fire form Brass for that 1 AR and when you resize smoke the brass and do not push the shoulder back more than say 3 thousandths. Also if say you can not get some cases to fire then you may have to single fire them as the C,O,L will probably be to long to fit the magazine as you will have to seat the bullet out far enough to contact the lands of the barrel in order to keep pressure of the brass against the bolt in order for them to fire. Also you will have to reduce the powder charge to a start load or maybe even below due to what could happen is excessive pressure. And then those rounds will function and fire fine but only that batch of fire formed brass. Of which again for an AR is a huge drawback. This is just a foot note. If you wish to know more do a search for Fire Form Brass. |
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Quoted:
I have this new upper in 300AAC. Was having tons of problems with it failing to fire and failing to extract. I picked up some PTG Go No-Go gauges from Midway to check the chamber. The bolt closes on both gauges. Is this a problem? if so, does that mean it is a bad barrel or is this something I can fix? Any assistance would be greatly appreciated, Thanks. Did you completely disassemble the bolt to check the headspace or just drop the gage in the chamber and drop the bolt? |
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A little update for you all. I appreciate all the help here...
When I tested with the gauges, I removed the extractor, but left the ejector. Then just hand slid the BCG in to battery with the gauges in place. It closes, locks and extracts both gauges. I can test again without the ejector but I do not think it will make a difference at this point. So I tested with another BCG today. The fail to fires ceased but I continued to have extraction problems and a lot of double feeds. I tried making several gas adjustments from under-gasing to over-gasing. I did set the gas up per the manufactures recommendations but that did not help at all. Here a few pictures I grabbed of the problems PICTURES I tested with 4 different ammo types across 3 different manufactures. I think my plan at this point is to RMA the entire upper. |
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First, the ejector gives you a lot of resistance when trying to close a bolt, which is why you should remove it when checking headspace. Some people get a "feel" for how much resistance the ejector spring provides, and that's OK for them, but a new user should know exactly what they're feeling when doing this test. I test new barrels with a bare bolt (I have one on hand that's completely stripped just for this purpose), and it's extremely clear when something works and when it doesn't.
The pictures show what looks to me like an ejection problem, and possible an extraction problem on top of it. It looks like the empty case is not being ejected, so it stays in the bolt until the new round from the magazine knocks it off. I'd look at the ejector in each bolt you've used with this gun to make sure the thing compresses AND pushes back out. If you RMA the gun, you'll have more data to provide to the technicians by doing this. Sorry you're having such problems. The 300 Blackout is a great round and a lot of fun to shoot. |
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Quoted:
A little update for you all. I appreciate all the help here... When I tested with the gauges, I removed the extractor, but left the ejector. Then just hand slid the BCG in to battery with the gauges in place. It closes, locks and extracts both gauges. I can test again without the ejector but I do not think it will make a difference at this point. So I tested with another BCG today. The fail to fires ceased but I continued to have extraction problems and a lot of double feeds. I tried making several gas adjustments from under-gasing to over-gasing. I did set the gas up per the manufactures recommendations but that did not help at all. Here a few pictures I grabbed of the problems PICTURES I tested with 4 different ammo types across 3 different manufactures. I think my plan at this point is to RMA the entire upper. Take the bolt out of the carrier. and remove the extractor and ejector. The carrier has a cam that will interfere with getting a good gage reading. Preferably, remove the barrel. Drop the gage it and with finger pressure only try and turn the bolt on the NOGO gage. In any case, a short headspace will not cause failure to fire. Those are failures to eject. Extractor, extractor spring most likely, ejector or ejector spring next. |
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I didn't have a tool to remove the ejector, but I will next week and will take the advice given on removing the ejector as well when checking for head space.
That said, the first BCG I used was a brand new one. The second BCG was from my other rifle. It's a fail zero bolt and I have never had any problems with it in my other rifles with extraction or otherwise. All the springs on this bolt looked and felt good. So I know this bolt to be good. But oddly still was having ejection problems. The ejection problems today were not like last week when the cases would not extract at all. Today they extracted, just not all the way. Most of them stuck around in the carrier and did not eject completely out. I believe this is what was causing my double feeds. On a positive note, all rounds today actually fired unlike before when I was getting a lot of fail to fires. Plus this has been a learning experience for me not only in the field, but on this thread alone. I very much appreciate this communities interests in sharing knowledge. I will see what the manufacture says. Honestly, a new upper out of the box should not do this. Everything is brand new. It's frustrating for me but I know this is a good round to shoot. I will get it running soon! |
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I didn't have a tool to remove the ejector, ... If your barrel is removed and you have a pin punch, you can remove the ejector by reinstalling the extractor, placing a empty case under the extractor and depressing the ejector. Now, slide all that into the barrel and rotate the bolt locked. That will hold the ejector depressed and you can tap out the ejector pin. You will need to find a suitable support for the bolt when you drive out the pin. You have to be careful when you remove the bolt from the barrel as the ejector and spring will want to fly out and disappear. wrapping it all up in a towel helps contain the parts. Installation is just the reverse, but a little fiddly as you have to align the slot in the ejector with the pin-hole. |
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Quoted:
If your barrel is removed and you have a pin punch, you can remove the ejector by reinstalling the extractor, placing a empty case under the extractor and depressing the ejector. Now, slide all that into the barrel and rotate the bolt locked. That will hold the ejector depressed and you can tap out the ejector pin. You will need to find a suitable support for the bolt when you drive out the pin. You have to be careful when you remove the bolt from the barrel as the ejector and spring will want to fly out and disappear. wrapping it all up in a towel helps contain the parts. Installation is just the reverse, but a little fiddly as you have to align the slot in the ejector with the pin-hole. Quoted:
Quoted:
I didn't have a tool to remove the ejector, ... If your barrel is removed and you have a pin punch, you can remove the ejector by reinstalling the extractor, placing a empty case under the extractor and depressing the ejector. Now, slide all that into the barrel and rotate the bolt locked. That will hold the ejector depressed and you can tap out the ejector pin. You will need to find a suitable support for the bolt when you drive out the pin. You have to be careful when you remove the bolt from the barrel as the ejector and spring will want to fly out and disappear. wrapping it all up in a towel helps contain the parts. Installation is just the reverse, but a little fiddly as you have to align the slot in the ejector with the pin-hole. Good information. I will tag that one in my head for later. I will ultimately get a tool for this but I like the work around. For the record...the manufacture has asked me to send the entire upper back. I will let them deal with this at this point. It was a brand new upper and out of the box this thing should have rocked...no excuses. I hope they do the right thing and replace it. |
| Buy one of THESE Bolt Assembly Blocks from the ARFCOM store. $15 well spent, in my estimation. You leave the ejector in, then put an empty case in the bolt face. The block holds the case in the right position to depress the ejector. Almost magic! |
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